Indirect immunofluorescence antibodies to Legionella pneumophila: frequency in a rural community

Abstract
The background prevalence of indirect immunofluorescence antibody to L. pneumophila in a rural community was determined by testing sera from 517 volunteers. The upper limit of normal antibody titer was 1:64 with L. pneumophila serogroup 1 (Philadelphia 1) used as antigen. High titers (.gtoreq. 1:128) were found in 13.2% of the sera and occurred with similar frequencies in males and females. In individuals 40 yr of age and older, high titers were 2.7 times as prevalent in males as females.